Mandibular Overdentures Retained by Conventional or Mini Implants

Inclusion Criteria: * Complete edentulism; * Request of implant stabilization of the existing lower conventional denture; * Clinically acceptable maxillary and mandibular complete dentures; * Adequate space in the anterior mandible for the placement of four mini implants and two conventional implants (regular diameter); * Ability to maintain adequate oral hygiene and clean dentures; * Systemic health status that permits minor surgical procedures; * Adequate understanding of written and spoken Portuguese; * Capacity of giving written informed consent. Exclusion Criteria: * Lack of minimum vertical mandibular bone height of 11mm in the interforaminal region; * Acute or chronic symptoms of parafunctional disorders; * History of radiation therapy to the orofacial region; * Specific conditions that may jeopardize the treatment, i.e. alcoholism and smoking; * Severe/serious illness that requires frequent hospitalization; * Impaired cognitive function; * Impossibility to return for evaluations/study recalls.